[quote author=Bob link=1145573673/75#75 date=1146779361]One driver in each box mounted with magnet in lower chamber, so "top" chamber now includes the center chamber also?

Continue running amp bridged with a "Y" in cable? Or, run each sub on it's own channel? It might have some kind of neat stereo thing, or it might just sound funky running it that way.

Bob [/quote]

No, each box would have the driver mounted on one end and a port on the other end, no more chambers. You'd just be able to easily convert it to the HWKenstein later.

Another alternative is to build HWKenstein exactly as described and leave the cap off of the original cab. Give me a few days to crunch some numbers first and get port lengths for your different options and do some modelling to be sure they all make sense. Plus I have another idea that I need to model first, and it might involve even less construction.

The bottom line is that you don't need different drivers or amp and you can put what you already constructed to good use. At most all you need is some wood and port(s) and end up with impressive bass.

Sometimes I forget and talk about what I would build for myself. I already have plenty of subs to choose from and most have much more output than sane people would want. I'm into this mode now where I want to outdo Dirt Dawg's Big Whistles and make my chair move with big LFE's.

Take the bottom driver out and clamshell it with the top driver. Wiring remains the same (opposite for each driver since they are still push/pull).

If you don't already have a 4" port, pick up a 13" piece of 4" PVC.

Block one of the bottom ports from the inside with a piece of wood.

Enlarge the other bottom port just so the PVC fits snugly from the outside (enlarge it to the top and center of the cab so you don't interfere with the bottom cap and try not to mess up your exterior finish work too much). This is just a test for you at first, so let the port stick outside the box. The tuning difference will be insignificant.

Try to smooth the interior and the exterior ends of the port as much as possible. Don't worry too much because without flares on both ends, you'll probably get port noise due to turbulence no matter what you do even though that interior corner will act kind of like a flair. Remember this is just a test, so ignore port noise.

Put the bottom cap on (leave the top cap off) and crank it up.

You now have a ported sub with a Vb (interior net volume) of right at 150L, with a port tuned to 19hz (actually a little lower due to port placement). You should have a gradual slope from 50hz down to -3db at 19hz and a -10db at 14hz, which should be offset by room gain unless you have an open room configuration, so a net in room close to flat down into the teens.

The exposed basket of the driver on top will be hidden by the old top chamber. That open chamber will have no effect on response at these subwoofer frequencies. You will have traded some amp power for a smaller box and your max output is 6db less than possible with the same total power and 4 times the Vb.

Let me know if that does it for you and I'll help you finalize it when I get back from the beach Monday. Gotta get back to burning CD's to bring with me to listen on Silver Iris OB-RLH's down at the beach.

I'm sure I can find a reason to "need" to go to Home Depot to get one more nail for the deck. A couple pieces of MDF and a lenth of 4" PVC may happen to fall into my truck, 'How'd that happen?' (just in case HWK needs steroids. Can ALLWAYS use MDF.)

Thanks again, John

Bob

p.s. John said, "I already have plenty of subs to choose from and most have much more output than sane people would want. I'm into this mode now where I want to outdo Dirt Dawg's Big Whistles and make my chair move with big LFE's."

This is a good thing!

Hey BTW John, how do you keep your projector bulb from exploding with the LFE's?

John, I bought "Master and Commander" based on Rap's recommendation a couple months ago. Very good movie. Was anxious to hear the LFE's.....My God man! I had to keep turning down the amp, AND reciever to keep Mr. Klop at bay. I see the potential of the LFE, but frustrated that I can't "get there from here".

I think I've got myself another LFE referance movie....

One thing I'll say about the Daytons, they must've been made by Timex, 'cause they take a lickin' and keep on tickin'.

Thats the movie we were seeing how much the big pair of SV subs could handle. we had to remove the wall lamps and stuff off the walls even before we turned the sunfire power subs loose.felt like the carpet was rippling under our feet.too bad it was my cousins system. Well maybe a good thing because my wife got pretty cranky during a couple cannon shots.she was on the deck outside and I got a earful when we left.

Hmmm Gex, I really hope it rains this weekend. Why you ask? Well you can't build a deck in the rain, BUT, you CAN tweek a sub! I'm looking forward to performing John's HWKenstien "adjustments" to the sub. I'm definetly missing something here in the LFE realm. In NO WAY am I rippling carpet much less 'wrecking the house'.

Try the simple one first. It may be enough. You can't beat that size, but port noise is my concern as an ultimate solution. Plus, you can squeeze in doing the new bottom port while she goes to the store. Then after dark (can't build pretty decks in the dark), you can swap the driver over to the top and be testing Master&Commander that night. The HWKenstein won't work with your current mains anyway and the single isobarik BR may be enough for now. That way you'll have a better idea of what you ultimately want (more extension, more max output, etc). Plus you can start tracking down your room rattles and get wifey used to the concept of high impact LFE's.

Oh, I almost forgot. Stop banging that back plate on your drivers. You have some good drivers and you don't want to mess them up.

As far as what I ultimately want,.... subsonic, no driver self destruction, good quality sound (doesn't have to be perfect. Remember it's not an audiophile listening room)

The mains John, are on "the cut list". They'll be going soon. I'd like to chat about those someday, as far as DIY options go. Just not in great detail at this point. --- Baby steps.

Wifey is getting "used to" overall volume capabilities of the overall system, but hasn't (obviously) had much in the way of LFE potential. :-*

I get this panicy chill in my spine when I hear that noise. Scrambling for the correct remote in a pile of 6 in the dark to turn down the volume is getting old. (LFE is done and gone by the time the I.F. hits the eye anyway >:()

I'm sure I'll be in the cave this weekend, a cuttin'. Shouldn't have a problem getting mods finished. I still can't post at home ::) so I'll be getting back with results on Monday.

Hey, by the way, Just for grins / in the name of science.... Those Radio Shack SPL meters are pretty cheap arn't they ($35?) Would it be worth the time/$ to get an A/B difference as far as max (unbottomed) output goes? What do you think?

Nothing like that is cheap down here. Once I finally found an SPL meter, it was over $150. While you are at Radio Shack, put up a programmable remote. Once you get it going then you have just 1 that controls everything. It's worth every penny and time spent setting it up. Generally you just need on/off for the PJ, on/off + volume for the receiver, on/off + guide + chan(+/-) + prev chan for DirecTV and cable boxes. I tried to put all functions of everything in mine, but ran out of memory, however, doing so gives you backup in case you lose a remote. I still don't understand how some things on some units can't be done without a remote. eg I can't even turn on my video enhancer unit, which centralizes all of my video sources, without a remote control. That's just absurd, but I have backup now and remotes all go in one secure box if I need them.

Re port noise, big 2" radius flares help tremendously, but eg with the HWKenstein that's a lot of air to push through a longish 4" port and you may get a high enough velocity in the port that turbulence is inevitable. With HT, a little port noise doesn't matter because there's plenty of other noise happening along with those LFE's that you don't hear it. Plus you have your PJ noise to overcome already. You'd have to be an organ music buff for it to be bothersome.

You may have missed an earlier question I had John, Do you do anything special to isolate the PJ from the LFE?I'm already getting a slight amount of "jitter" on the screen from the HWK during 'Darla and the cannons'. (worried about bulb failure)

Why is the meter so expensive there, is it the cost of the equipment, or shipping? If it's the cost of the item, let me know if I can ship you something?

A buddy has a Sony 'Commander' he lent me. It won't control the Sanyo PJ for some reason. I got frustrated and put it down a month ago or so. I'll pick it back up one of these days.

My homemade PJ mount is connected to one of support columns of a concrete wall, so only earthquakes can make it wiggle. I don't think the LFE's will directly impact the bulb, but I agree that if what they are mounted to vibrates a lot it can't be good for the bulb at operating temperature. Test it using a slow tone sweep with the PJ off first just to be sure you aren't stimulating a resonance in whatever supports the PJ. You need to do that anyway to tie down room rattles.

Re the SPL meter, I needed it that week, plus my M/C doesn't work online, so the timing and cost didn't justify having someone buy it stateside and ship it to me. Hard to find stuff can have silly prices, but our full time maid/nanny is only $200/mo and my skilled builder/helper is extremely happy with $20/day, so I don't complain, especially with shorts and tshirt weather year round and no A/C or heat needed. Where I live it's lows of 60-70 at night and highs of maybe 80, year-round. The sun can be brutal, but in the shade is always pleasant with a breeze. I die down at sea level at the beach though.

I just use the top end Radio Shack remote, the one you can just point another remote at and copy the controls you want. Quick and simple.